The logic model that implicitly drives most professional development (PD) efforts asserts that PD leads to changes in teacher knowledge and beliefs, which leads to improved classroom practice, and ultimately, better student outcomes. However, efforts to study the impacts of PD programs are often hampered by the scarcity of high-quality instruments. This paper describes the development of a set of learning-theory aligned instruments including: coupled teacher and student content assessments that measure conceptual understanding in each of four topics at two different grade levels (upper elementary and middle school); a survey of teacher beliefs about effective science instruction; and a classroom observation protocol. These instruments have been used in a number of research and evaluation projects to study professional development and its impact on teacher content knowledge, beliefs, classroom practices, and/or student achievement.